Abstract:China is the largest country of cultivating sweet potato in the world. The resources of sweet potato vines (SPV) are huge. To exploit the rich resources, SPV of XuShu 18 was selected as raw materials since it is cultivated in China widely. Polysaccharide from SPV was extracted by pilot instrument and precipitated by ethanol. The decolouring technology was studied. By primary purification, we obtained the polysaccharide from SPV (PSPV) and studied its physical and chemical characters. Using DEAE-cellulose column and NaCl solution as eluting reagent, three kinds of pure polysaccharide, named PSPVⅠ, PSPVⅡ and PSPVⅢ respectively, were obtained. Then the molecular weight distribution and sugar compositions were studied using High Performance Gel Filtration Chromatography and GC. The followings are the results. PSPVⅠ was separated from PSPV which was extracted from SPV harvested in the middle of June. Its M.W. is 6.278×104 D and is mainly composed of Xylose, Mannose and Glucose. PSPVⅡ and PSPVⅢ were separated from PSPV which was extracted from SPV harvested in the middle of October. Their M.W. are 3.801×104 D and 1.418×104 D respectively. PSPVⅡ is mainly composed of Mannose and Galactan. PSPVⅢ is mainly composed of Glucose, Xylose and Rhamnose. The results provide theoretical basis for the utilization of SPV.